1. Field of the Invention
The present invention relates generally to endless track mechanisms for motorized vehicles, and more specifically to a track assembly for removable installation about the road wheels of a wheeled vehicle. The present track assembly is particularly well adapted for removable installation about the existing pneumatic tires of a relatively small skip loader and end loader type machinery and equipment (e.g., "Bobcat".TM., vehicles) and provides the traction benefits of tracked type vehicles for such machinery.
2. Description of the Related Art
Relatively small and light utility vehicles such as small end loaders, skip loaders, and the like are conventionally equipped with four pneumatic tires for traction, with many utilizing differential braking for steering control. The fact that all of the wheels remain in alignment at all times due to their inability to change direction for steering, provides a basis for the addition of some form of endless track or belt about the wheels on each side of the vehicle to provide improved traction and flotation over loose and/or soft surfaces.
The above described concept has been implemented generally in the past, as exemplified by various earlier patent publications discussed further below. However, the efforts made in the past to produce a practicable track system for such wheeled vehicles have been less than totally satisfactory for various reasons, as noted further below.
Accordingly a need will be seen for a track assembly for wheeled vehicles, with the present track assembly providing removable installation on the road wheels of various types of skid steering type utility machines. The present track assembly comprises a plurality of identical links or segments, with each segment having a pair of connecting tongues or lugs extending in one direction from each end thereof and a single connecting tongue or lug extending in the opposite direction from each end of each link. The single tongues are each aligned with the gap between the opposed two tongues of an adjacent link, with a single bolt or pin being installed through the mating tongues at each end of the links to assemble the identical links. The present system provides greatly improved simplicity and efficiency over other removably installable track systems which require separate connecting clevises or other links between each of the track segments or links, as well as providing other benefits.
A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 2,726,904 issued on Dec. 13, 1955 to Mieczyslaw G. Bekker, titled "Endless Track," describes a relatively light weight track system comprising two different types of track sections or links alternately secured together, unlike the single type of link of the present invention which may be assembled with identical links to form a length of track. Also, the Bekker track links have depressed central sections which are engaged by the sprocket wheels of a tracked type vehicle (e.g., Caterpillar.TM.--type tractor, etc.) and which ride in the center depression of the idler or "buggy" (bogy) wheels of such a machine. This arrangement is unsuitable for use with a vehicle having road wheels, as the central sections would ride over the raised center areas of the tires and would immediately slip laterally from the tires, as no lateral retaining means is provided by Bekker.
U.S. Pat. No. 4,089,565 issued on May 16, 1978 to George A. Loegering et al., titled "Removable Track Structure For Wheeled Vehicles," describes a track assembly comprising a series of identical individual links or sections. The links include depending end portions which serve to surround the sides of the tires partially in order to preclude slippage of the track assembly from the wheels. In one embodiment, each section has a lug extending from each end portion thereof which is captured between cooperating flanges of the end portion of the adjacent segment. The connecting pin is thus aligned generally with the track segment, making it difficult to access the end of the connecting pin to drive it out of the mating lug and flanges. In another embodiment, the two closely spaced end flanges extend to one side of the end portion, with the outer one of the two also extending forwardly and offset to fit between the two end flanges of the adjacent track segment. While this positions the connecting pins between each track segment for ease of access to the inboard end of the pin, the offset configuration of the single flange or lug results in asymmetrical bending forces being developed in the joint in addition to the shear forces across the connecting pin. Moreover, it is noted that Loegering et al. do not disclose any means of retaining the connecting pins in the mating flanges and lugs of their track segments; it would appear that these pins could work loose. In contrast, the present track assembly provides means for positively securing the pins through the mating tongues of adjacent track sections or links. Moreover, the mating extensions or tongues for connecting track segments of the present invention together are straight with no lateral offsets, thus providing pure shear forces across the connecting pins, unlike Loegering et al.
U.S. Pat. No. 4,176,887 issued on Dec. 4, 1979 to Gunther Alpers et al., titled "Endless Track Traveling Mechanism," describes a track assembly for use with conventional tracked vehicles having sprocketed drive wheels and bogy or idler wheels. As the track segments each include depending portions for engaging the protruding teeth of the sprocket wheels, the Alpers et al. track is more closely related to the track of the Bekker '904 U.S. Patent discussed further above than to the present track assembly; the Alpers et al. track cannot be applied to a wheeled vehicle.
U.S. Pat. No. 5,058,963 issued on Oct. 22, 1991 to Hagen H. Wiesner et al., titled "Belt-Type Caterpillar For Track-Laying Vehicles And Snowmobiles," describes a track assembly in which each track segment includes a plurality of resilient lugs and opposed teeth which are connected together by resilient belts. The belts include looped ends with lateral passages for installing lateral connecting bolts or pins therethrough. The teeth depend from the track towards the drive wheels and engage the wheels of the vehicle to maintain the alignment of the track on the wheels. Passages are also provided through the track to engage the teeth of the drive wheels. Thus, the Wiesner et al. track assembly is more closely related to the track assemblies of the Bekker '904 and Alpers et al. '887 U.S. Patents discussed further above, than to the present track assembly for removable installation on a wheeled vehicle.
U.S. Pat. No. 5,284,387 issued on Feb. 8, 1994 to George A. Loegering, titled "Removable Flexible Track Belt And Track Section Therefore (sic)," describes a track assembly having depending end flange portions for extending partially about the sides of the tires of a wheeled vehicle. All of the segments of the track assembly are identical to one another. However, each of the flanges includes a pair of lugs extending in opposite directions therefrom, with this symmetrical configuration precluding the direct attachment of adjacent segments to one another, as provided by the present track assembly. Loegering requires intermediate connecting links to join his track segments, thus adding to the number of parts and complexity of the assembly.
U.S. Pat. No. 5,616,193 issued on Apr. 1, 1997 to Erik G. S. Nordstrom et al., titled "Pneumatic Tires With Cooperating Track," describes in general a track assembly which may be applied to the pneumatic tires of a wheeled vehicle. However, the disclosure is primarily directed to a provision for internally supporting a deflated tire without undue wear thereto, including certain rubber compounds providing suitable durability for the deflated tire. Nordstrom et al. do not disclose any specifics relating to the track segment connecting means or other details of such a track assembly.
Finally, U.S. Pat. No. 5,951,124 issued on Sep. 14, 1999 to Ronald J. Hoffart, titled "Self-Cleaning Track," describes a track configuration similar to that of the identical, symmetrical track segments of the Loegering '387 U.S. Patent discussed further above, requiring the installation of intermediate links between each track segment for the assembly of the track. While Hoffart provides other distinctions over the track configuration of the '387 Loegering U.S. Patent, the requirement for a multitude of intermediate links for assembling his track segments to form a complete track assembly, results in a relatively complex assembly with considerably more parts than the track assembly of the present invention, with the present invention providing further benefits as well.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.